Fishermen have long known that materials floating on the ocean surface, especially in tropical waters, attract many species of game and forage fish. Natural materials known to attract fish have included logs, palm fronds, bamboo, shipping crates and other flotsam, as well as living organisms, such as porpoises and dolphins. Commercial and recreational fishermen have taken advantage of these aggregations of floating materials and game fish by fishing near the floating material in order to catch the associated fish.
As will be readily recognized, this is fishing by mere happenstance, where the "luck" is enhanced by the chance occurrence of floating materials and the further chance that those floating materials may have attracted desirable fish.